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TPA3116D2: Frequency-Dependent Output Behavior of TPA3112D2-Q1

Harikrishnan k
Prodigy 10 points
Part Number: TPA3116D2

Tool/software:

Hi E2E Team,

We are currently using the TPA3112D2-Q1 in our design with the following configuration:

  • Modulation Mode: BD

  • Output Configuration: BTL(Right channel used, Left channel unconnected)

  • Gain Setting: 36 dB

  • PVCC Supply Voltage: 24V

  • Switching Frequency: 400kHz

  • Load: 33uH and 4 ohm in series

During testing, we observed the following behavior:

  • At 200Hz input, with 588mVpp (208mVrms) signal, the output measured 36.4Vpp (12.87Vrms) and 10.5Ipp (3.71Irms).

    • This results in an effective gain of approximately 35.8dB and a calculated output power of 47.7W.

       

      The waveform appears clean and consistent at this frequency.

      • However, when the input frequency is increased to 8kHz, we noticed:

        • A reduction in output wattage

        • A phase difference between voltage and current waveforms

        • Distortion in the voltage waveform shape

        We have attached the relevant waveforms for your reference.

         

        • Could you please help us understand the possible reasons for this frequency-dependent behavior? Specifically, we are interested in knowing:

          1. Whether this is expected due to internal characteristics of the device at higher frequencies

          2. If layout, filtering, or load impedance could be contributing factors

          3. Any recommendations to mitigate this issue and maintain consistent output across a wider frequency range

          Your insights would be greatly appreciated.

          Schematic also attached with thistpa3116_Schematic.pdf

Thanks and Regards

Hari

  • 0
    TI__Mastermind 49800 points

    Hi Hari

    It's most possibly the high order harmonic been amplified by the output LC filter and your load side inductance. Only voltage waveform will be clearly affected. The load 33uH+4ohm is very large impedance under high frequency, so the current will be more clean, only the 8KHz fundamental frequency left.

    This phenomenon usually won't cause trouble, as the most of the high order are out of audio frequency band. If you could add the audio filter on the the output, like AES17 20KHz, you'll see the output is quite clean.